Portable viewing/listening system

ABSTRACT

A main device receives program data provided through broadcasting, internally stores the received program data, and transfers the stored program data to a portable device. Herein, one program data is constituted by a plurality of program components (video, audio, closed caption, and the like). The main device assigns transfer priorities to each program component constituting one program data, and then discretely transfers the program components respectively in the direction of a time axis in the order of the assigned transfer priorities. By discretely transferring data, some of the program components may possibly be entirely transferred to the portable device even when data transfer is discontinued in a short time. Therefore, users can enjoy the entire program by playing-back the already-transferred program components.

This application is a divisional of application Ser. No. 09/432,389,filed on Nov. 8, 1999, now U.S. Pat. No. 6,959,221 which is a nationalstage application of International Application No. PCT/JP99/01715, filedon Apr. 1, 1999.

TECHNICAL FIELD

The present invention relates to portable viewing/listening systems, andmore particularly to a portable viewing/listening system in whichprogram data that is received by a fixedly or semi-fixedly installedmain device is transferred to an easy-to-carry portable device so as tobe played-back in the portable device and thereby provide a user of theportable device with the program data.

BACKGROUND ART

Thanks to multi-channeled broadcast and developing video servicesthrough communications, the number of programs which are available forgeneral users has been increasing. However, the users' spare-time forwatching the programs is limited within a day. Accordingly, the userscannot always watch every program that they are interested in.

Recently, a portable viewing/listening system which enables the users towatch programs in their spare time (during lunch or in transit) has beenproposed. A conventional portable viewing/listening system isconstituted by a main device which is installed in a house and aneasy-to-carry portable device. The main device is at least capable ofreceiving program data that is provided through broadcasting,internally-storing the received program data, and transferring thestored program data to the portable device.

The conventional portable viewing/listening system, however, takes along time to transfer the program data from the main device to theportable device. Accordingly, if the users run out of time and thus stopdata transfer halfway through, the program data is not entirelytransferred, and thus the users cannot enjoy the entire program.

FIG. 18 is a diagram illustrating a data transfer mode which is adoptedin the conventional portable viewing/listening system. Hereinafter, byreferring to FIG. 18, problems that are associated with the conventionalsystem are described in more detail.

FIG. 18( a) shows a time transition of data constituting a program to bebroadcast. In FIG. 18( a), a lateral axis indicates a lapse of timeduring broadcast, and a vertical axis indicates a bit rate duringbroadcast, respectively. To be more specific, FIG. 18( a) shows thatProgram 1 is broadcast between Time t0 and Time t1, Program 2 isbroadcast between Time t1 and Time t2, and Program 3 is broadcastbetween Time t2 and Time t3, respectively. The Program 1, Program 2, andProgram 3 are respectively provided with audio, closed caption, andvideo as program components (mono-media constituting a program). For thesake of clarity, it is herein assumed that a length of broadcast timefor the Program 2 (t2−t1) is equal to the length of broadcast time forthe Program 3 (t3−t2), and a length of broadcast time for the Program 1(t1−t0) is exactly twice the length of broadcast time for the Program 2(or the Program 3). It is also assumed that a bit rate for therespective program components remains invariant no matter which Program,and thus a ratio among a bit rate of closed caption bc, bit rate ofaudio ba, and bit rate of video by is always 1:2:4.

FIG. 18( b) shows a time transition which takes place when the programdata is transferred from the main device to the portable device in theconventional portable viewing/listening system. In FIG. 18( b), alateral axis indicates a lapse of time in a data transfer operation, anda vertical axis indicates a bit rate during transfer, respectively. Asshown in FIG. 18( b), transfer of the program components of the Program1, Program 2, and Program 3 is completed between Time t4 and Time t9. InFIG. 18( b), unlike the bit rate during broadcast shown in FIG. 18( a),the bit rates for the program components during transfer are eachcompressed or extended in the direction of a time axis according tocharacteristics of data for the respective program components. However,the program components herein are basically transferred in the sameorder as those during broadcast. This means that every program componentof the Program 1 is transferred between Time t4 and Time t7, everyprogram component of the Program 2 is transferred between Time t7 andTime t8, and every program component of the Program 3 is transferredbetween Time t8 and Time t9, respectively. A ratio among (t7−t4),(t8−t7) and (t9−t8), all of which indicate a length of time which istaken to transfer each Program, is 2:1:1. This is equal to the ratioamong (t1−t0), (t2−t1) and (t3−t2), all of which indicate a length ofbroadcast time for each Program. Assuming that a total bit rate forclosed caption, audio and video during transfer is a -time as much as atotal bit rate during broadcast, a ratio between a length of broadcasttime of a certain program and a length of time which is taken totransfer the program is always α:1.

FIG. 18( c) shows a case where a transfer of program data isdiscontinued halfway at Time to in the conventional portableviewing/listening system. In this example, the Time ta is assumed tosatisfy t7<ta<t8. As transfer of the program data is discontinued in themiddle of the Program 2 between Time t7 and Time t8, the entire data ofthe Program 1 and a partial amount of the data of the Program 2 from itsbeginning to Time ta is transferred to the portable device. However, asto the remaining portion of the data of the Program 2 and the entiredata of the Program 3, none of the program components, i.e., closedcaption, audio and video, included therein is transferred to theconventional portable viewing/listening system. As to thenot-transferred part of data, the portable device does not inform theusers what the non-transferred data is. Therefore, the users cannot evenknow whether or not the non-transferred data is interesting enough towatch.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a portableviewing/listening system which guarantees the minimum play-back qualitythat is required for the users on the portable device side even whendata transfer from the main device to the portable device isdiscontinued in a short time.

The present invention has the following features to attain the objectdescribed above.

A first aspect of the present invention is directed to a portableviewing/listening system in which program data that is received by afixedly or semi-fixedly installed main device is playedback in aneasy-to-carry portable device so as to provide a user with the programdata.

The main device of the first aspect comprises:

receiving means for receiving program data that is provided throughbroadcasting;

primary storing means for storing the program data received by thereceiving means;

transfer priority assigning means for assigning transfer priorities toeach program component constituting the program data that is stored inthe primary storing means; and

transferring means for discretely transferring, to the portable device,each of the program components of the program data that is stored in theprimary storing means in the direction of a time axis in the order ofthe assigned transfer priorities.

The portable device of the first aspect comprises:

secondary storing means for storing the program components to bediscretely transferred from the transferring means;

re-constructing means for re-constructing program data included in anyprogram that is desired to played-back from the program components whichare stored in the secondary storing means; and

playing-back means for playing-back the program data that isre-constructed by the re-constructing means.

As described above, in the first aspect, each program componentconstituting the program data simultaneously received by the main deviceis assigned a transfer priority, and the program components arediscretely transferred, to the portable device, in the direction of thetime axis in the order of the assigned transfer priorities. Therefore,even if data transfer from the main device to the portable device isdiscontinued in a short time (i.e., prematurely), there is a highpossibility that some of the program components are entirely transferredto the portable device. Accordingly, the users can enjoy, albeitincomplete, the entire program by playing-back the already-transferredprogram components.

According to a second aspect of the present invention, in accordancewith the first aspect, the transfer priority assigning means assignstransfer priorities to each of the program components in such a mannerthat a program component with a smaller amount of data has a highertransfer priority.

As described above, in the second aspect, any program component having asmaller amount of data has a higher transfer priority from the maindevice to the portable device. This means that a length of time which istaken to transfer the program component having the higher transferpriority is shorter. Consequently, if data transfer is presumablydiscontinued in the system of the present invention and in theconventional one at the same time, the number of program componentswhich are successfully transferred to the portable device in the systemof the present invention is larger.

According to a third aspect of the present invention, in accordance withthe second aspect, the main device further comprises transfer prioritydefining means for previously defining transfer priorities by default toevery type of the program components, and the transfer priorityassigning means assigns, in accordance with a definition provided by thetransfer priority defining means, the transfer priorities by default toeach of the program components.

As described above, in the third aspect, each of the program componentsis assigned, in the main device, the transfer priorities by defaultaccording to the type thereof. Therefore, the program components can betransferred in an order which is appropriately determined by thecharacteristics thereof.

According to a fourth aspect of the present invention, in accordancewith the third aspect, when the plurality of program data stored in theprimary storing means are collectively transferred to the portabledevice, the transferring means selects any program component having thesame transfer priority from each of the program data, combines theselected program components into a unit, and then discretely transfersthe combined unit in the direction of the time axis in the order of thetransfer priorities that are assigned to every combined unit.

As described above, in the fourth aspect, when a plurality of programdata is collectively transferred to the portable device, the data is nottransferred on a program basis but instead on a transfer priority basis.That is, the program components having the same transfer priority areselected from the respective program data, the selected programcomponents are combined to a unit, and then the combined unit istransferred in the order of the transfer priorities which are assignedto every combined unit. Therefore, the programs are assigned transferpriorities in a fair manner, and as a result, variation in arriving timeof the programs can be prevented.

According to a fifth aspect of the present invention, in accordance withthe fourth aspect, types of the program components are classified into aplurality of classes by the transfer priority defining means. Further,the transfer priority assigning means checks every class for thetransfer priorities by default which are assigned to each of the programcomponents, and then changes, in accordance with a result of the check,the transfer priorities by default which are assigned to each of theprogram components on a class basis, as required.

As described above, in the fifth aspect, the types of the programcomponents are classified into a plurality of classes, and the transferpriorities are checked on a class basis before making a change, if any.Therefore, the transfer priorities can be managed on a class basis.

According to a sixth aspect of the present invention, in accordance withthe fifth aspect, when no program component in the same class has avalue which is defined as being a top transfer priority therein, thetransfer priority assigning means changes a value of a program componentbeing currently the highest transfer priority in the class to the valuewhich is defined as being the top priority therein.

As described above, in the sixth aspect, even if the types of theprogram components in the same class are varying, some of the programcomponents are managed to reach the portable device when the first unitfor each class is transferred.

According to a seventh aspect of the present invention, in accordancewith the first aspect, the main device further comprises programcomponent generating means for generating a new program component fromthe program components of the program data received by the receivingmeans, and the storing means adds the program component that is newlygenerated by the program component generating means to the program datareceived by the receiving means and stores the same.

As described above, in the seventh aspect, another program component canbe newly generated from the received program components and transferred.It is effective for a case where the received program data ishierarchically encoded into a plurality of layers so that the programcomponents in the respective layers are transferred, or for a case wherethe received detailed video is decimated to generate and transfer anon-detailed video.

According to an eighth aspect of the present invention, in accordancewith the first aspect, when any data of the program component of theprogram data that is re-constructed by the re-constructing means isdiscontinued halfway during play-back by the playing-back means, theportable device further comprises replacing means for having any otherprogram component being not currently played-back to play-back as areplacement.

As described above, in the eighth aspect, the program component whichwas not entirely played-back due to the discontinued data transfer isreplaced by any other program component to be played-back. Therefore,the users can enjoy the entire program. According to a ninth aspect, inthe eighth aspect, the program component which was not entirelyplayed-back due to the discontinued data transfer is replaced by anyother program component to play-back. Therefore, the users can enjoy theentire program.

According to a ninth aspect of the present invention, in accordance withthe eighth aspect, the protable device further comprises prentationpriority defining means for previously defining presentation prioritiesto each type of the program components, and the replacing meansdetermines a program component to be played-back as a replacement inaccordance with the definition that is provided by the presentationpriority defining means.

As described above, in the ninth aspect, the portable device is set todetermine the program component as a replacement in accordance with thepresentation priorities which are defined to every type of the programcomponents. Therefore, the program components can be replaced to beplayed-back in an order which is suitably determined by thecharacteristics thereof.

According to a tenth aspect of the present invention, in accordance withthe ninth aspect, types of the program components are classified into aplurality of classes by the presentation priority defining means, andthe replacing means determines a program component to be played-back asa replacement from among the program components belonging to the sameclass as does the program component discontinued during play-back.

As described above, in the tenth aspect, the replacing order to beplayed-back can be managed on a class basis.

According to an eleventh aspect of the present invention, in accordancewith the first aspect, the main device and the portable device arestructured to be electrically interconnectable, and the transferringmeans online-transfers each program component of the program data thatis stored in the primary storing means directly to the portable device.

As described above, in the eleventh aspect, the main device and theportable device are electrically interconnectable. Consequently, programdata can be transferred on-line.

According to a twelfth aspect of the present invention, in accordancewith the eleventh aspect, the main device further comprises attachingmeans for allowing the portable device to be electrically connected, andcharging means for supplying power to charge the portable device whenthe portable device is attached to the attaching means. Further,according to the twelfth aspect the portable device also comprises abattery to be charged by the power which is supplied from the chargingdevice.

As described above, in the twelfth aspect, transfer of the program dataand charging of the portable device can be done at the same time.

According to a thirteenth aspect of the present invention, in accordancewith the first aspect, the transferring means offline-transfers eachprogram component of the program data that is stored in the primarystoring means to the portable device through a recording medium.

As described above, in the thirteenth aspect, data can be off-linetransferred from the main device to the portable device through arecording medium. Therefore, such a structure eases restrictions whichare imposed on the physical layout of the main device and the portabledevice. Furthermore, a plurality of recording media will increase asubstantial memory capacity.

According to a fourteenth aspect of the present invention, in accordancewith the thirteenth aspect, the main device further comprises writingmeans for writing any program component to be transferred to theportable device into the recording medium, and the portable devicefurther comprises reading means for reading the program component thatis recorded in the recording medium.

According to a fifteenth aspect of the present invention, in accordancewith the first aspect, the receiving means receives program data througha computer network.

A sixteenth aspect of the present invention is directed to a main devicewhich is used in a state of being fixedly or semi-fixedly installed, andwhich is used to transfer any received program data to an easy-tocarryportable device. The main device of the sixteenth aspect comprises:

receiving means for receiving program data that is provided throughbroadcasting;

primary storing means for storing the program data received by thereceiving means;

transfer priority assigning means for assigning transfer priorities toeach program component constituting the program data that is stored inthe primary storing means; and

transferring means for discretely transferring, to the portable device,each of the program components of the program data that is stored in theprimary storing means in the direction of a time axis in the order ofthe assigned transfer priorities.

As described above, in the sixteenth aspect, each of the programcomponents constituting program data simultaneously received is assigneda transfer priority, and the program components are discretelytransferred, to the portable device, in the direction of the time axisin the order of the assigned transfer priorities. Therefore, even whendata transfer to the portable device is discontinued in a short time,some of the program components may possibly be entirely transferredthereto. Accordingly, the users can enjoy the whole program, albeitincomplete, by playing-back the already-transferred program components.

According to a seventeenth aspect of the present invention, inaccordance with the sixteenth aspect, the transfer priority assigningmeans assigns transfer priorities to each program component in such amanner that a program component with a smaller amount of data has ahigher transfer priority.

As described above, in the seventeenth aspect, any program componenthaving a smaller amount of data has the higher transfer priority. Thismeans that a length of time which is taken to transfer the programcomponent having the higher transfer priority is shorter. Consequently,if data transfer is presumably discontinued in the system of the presentinvention and in the conventional one at the same time, the number ofprogram components that are successfully transferred to the portabledevice in the system of the present invention is larger.

According to an eighteenth aspect of the present invention, inaccordance with the seventeenth aspect, the main device furthercomprises transfer priority defining means for previously definingtransfer priorities by default to each type of the program components,and the transfer priority assigning means assigns the transferpriorities by default to each of the program components in accordancewith a definition which is provided by the transfer priority definingmeans.

As described above, in the eighteenth aspect, each of the programcomponents is assigned the transfer priorities by default according tothe type thereof. Therefore, the program components can be transferredin an order that is appropriately determined by the characteristicsthereof.

According to a nineteenth aspect of the present invention, in accordnacewith the eighteenth aspect, when the plurality of program data stored inthe primary storing means are collectively transferred to the portabledevice, the transferring means selects any program component having thesame transfer priority from each of the program data, combines theselected program components into a unit, and then discretely transfersthe combined unit in the direction of the time axis in the order of thetransfer priorities which are assigned to every combined unit.

As described above, in the nineteenth aspect, when a plurality ofprogram data are collectively transferred to the portable device, thedata is not transferred on a program basis but instead on a transferpriority basis. That is, the program components having the same transferpriority are selected from the respective program data, the selectedprogram components are combined to a unit, and then the combined unit istransferred in the order of the transfer priorities which are assignedto every combined unit. Therefore, the programs are assigned transferpriorities in a fair manner, and as a result, variation in arriving timeof the programs can be prevented.

According to a twentieth aspect of the present invnetion, in accordancewith the nineteenth aspect, types of the program components areclassified into a plurality of classes by the transfer priority definingmeans. Further, the transfer priority assigning means checks every classfor the transfer priorities by default which are assigned to each of theprogram components, and then changes, in accordance with a result of thecheck, the transfer priorities by default which are assigned to each ofthe program components on a class basis, as required.

As described above, in the twentieth aspect, the types of the programcomponents are classified into a plurality of classes, and the transferpriorities are checked on a class basis before making a change, if any.Therefore, the transfer priorities can be managed on a class basis.

According to a twenty-first aspect of the present invention, inaccordance with the twentieth aspect, when no program component in thesame class has a value which is defined as being a top transfer prioritytherein, the transfer priority assigning means changes a value of aprogram component being currently the highest transfer priority in theclass to the value which is defined as being the top priority therein.

As described above, in the twenty-first aspect, even when the types ofthe program components in the same class are varying, some of theprogram components are managed to reach the portable device when thefirst unit for each class is transferred.

According to a twenty-second aspect of the present invention, inaccordance with the sixteenth aspect, the main device further comprisesprogram component generating means for generating a new programcomponent from the program components of the program data received bythe receiving means. Further, according to the twenty-second aspect, thestoring means adds the program component that is newly generated by theprogram component generating means to the program data received by thereceiving means, and stores the same.

As described above, in the twenty-second aspect, another programcomponent can be newly generated from the received program componentsand is transferred. It is effective for a case where the receivedprogram data is hierarchically encoded into a plurality of layers sothat the program components in the respective layers are transferred, orfor a case where the received detailed video is decimated to generateand transfer a non-detail video.

A twenty-third aspect of the present invention is directed to a portabledevice for receiving and playing-back program data that is received by afixedly or semi-fixedly installed main device so as to provide a user ofthe portable device with the received program data. The portable deviceof the twenty-third aspect comprises:

secondary storing means for storing each program component of theprogram data to be discretely transferred from the main device;

re-constructing means for re-constructing program data of a program thatis desired to be played-back from the program components stored in thesecondary storing means; and

playing-back means for playing-back the program data that isre-constructed by the re-constructing means.

As described above, in the twenty-third aspect, in a case where theprogram components of the program data are discretely transmitted fromthe main device, the program data that is included in any program whichis desired to be played-back can be re-constructed from the receivedprogram components and is played-back.

According to a twenty-fourth aspect of the present invention, inaccordance with the twenty-third aspect, when data of the programcomponent of the program data which is re-constructed by there-constructing means is discontinued halfway during play-back by theplaying-back means, the portable device further comprises replacingmeans for having any other program component being not currentlyplayed-back to be played-back as a replacement.

As described above, in the twenty-fourth aspect, the program componentwhich was not entirely played-back due to a discontinued data transferis replaced by any other program component to be played-back. Therefore,the users can enjoy the entire program.

According to a twenty-fifth aspect of the present invention, inaccordance with the twenty-fourth aspect, the portable device furthercomprises presentation priority defining means for previously definingpresentation priorities to each type of the program components, and thereplacing means determines a program component to be played-back as areplacement in accordance with a definition which is provided by thepresentation priority defining means.

As described above, in the twenty-fifth aspect, the portable device isset to determine the program component as a replacement in accordancewith the presentation priorities which are defined to every type of theprogram components. Therefore, the program components can be replaced tobe played-back in an order which is suitably determined by thecharacteristics thereof.

According to a twenty-sixth aspect of the present invention, inaccordance with the twenty-fifth aspect, types of the program componentsare classified into a plurality of classes by the presentation prioritydefining means, and the replacing means determines a program componentto be played-back as a replacement from among the program componentsbelonging to the same class as does the program component that isdiscontinued during play-back.

As described above, in the twenty-sixth aspect, the replacing order tobe played-back can be managed on a class basis.

A twenty-seventh aspect of the present invention is directed to a methodof transferring program data that is received by a fixedly orsemi-fixedly installed main device to an easy-to-carry portable device.The method comprises the steps of:

receiving program data that is provided through broadcasting;

storing the received program data;

assigning transfer priorities to each program component constituting thestored program data; and

discretely transferring, to the portable device, each of the programcomponents of the stored program data in the direction of a time axis inthe order of the assigned transfer priorities.

As described above, in the twenty-seventh aspect, each program componentconstituting the program data that is simultaneously received by themain device is assigned a transfer priority, and the program componentsare discretely transferred, to the portable device, in the direction ofthe time axis in the order of the assigned transfer priorities.Therefore, even if data transfer from the main device to the portabledevice is discontinued in a short time (i.e., prematurely), there is ahigh possibility that some of the program components are entirelytransferred to the portable device. Accordingly, the users can enjoy,albeit incomplete, the entire program by playing-back thealreadytransferred program components.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the structure of a portableviewing/listening system according to a first embodiment of the presentinvention.

FIG. 2 is a diagram exemplarily showing a storage list which is storedin a memory 112 in a main device 1 shown in FIG. 1.

FIG. 3 is a flowchart illustrating an operation that is performed on themain device side when program data is transferred from the main device 1to a portable device 2 in the portable viewing/listening system of thefirst embodiment of the present invention.

FIG. 4 is a flowchart illustrating a detailed operation of a subroutinestep S103 in the flowchart of FIG. 3.

FIG. 5 is a diagram exemplarily showing a transfer priority table whichis stored in the memory 112 in the main device 1 shown in FIG. 1.

FIG. 6 is a diagram exemplarily showing a receipt list which is storedin a memory 208 in the portable device 2 shown in FIG. 1.

FIG. 7 is a flowchart illustrating an operation of the portable device 2when receiving program data that is transferred from the main device 1in the portable viewing/listening system of the first embodiment of thepresent invention.

FIG. 8 is a flowchart illustrating how the portable device 2 is operatedto play-back a program in the portable viewing/listening system of thefirst embodiment of the present invention.

FIG. 9 is a diagram exemplarily showing a class table which is stored inthe memory 208 in the portable device 2 shown in FIG. 1.

FIG. 10 is a diagram illustrating how data is transferred in theportable viewing/listening system in FIG. 1.

FIG. 11 is a diagram showing a time transition which takes place duringa program transfer in a case where data to be transferred includes adigest video in the portable viewing/listening system in FIG. 1.

FIG. 12 is a diagram exemplarily showing a storage list to be generatedwhen the received data includes a digest video in the main device 1 inFIG. 1.

FIG. 13 is a diagram exemplarily showing a receipt list to be generatedwhen the data that is transferred from the main device 1 includes adigest video in the portable device 2 in FIG. 1.

FIG. 14 is an outer perspective diagram showing the physical structureof a portable viewing/listening system according to a second embodimentof the present invention.

FIG. 15 is a block diagram showing the electric structure of theportable viewing/listening system according to the second embodiment ofthe present invention.

FIG. 16 is an outer perspective diagram showing the physical structureof a portable viewing/listening system according to a third embodimentof the present invention.

FIG. 17 is a block diagram showing the structure of a portableviewing/listening system according to a fourth embodiment of the presentinvention.

FIG. 18 is a diagram illustrating a data transfer system which isadopted in a conventional portable viewing/listening system.

DETAILED DESCRIPTION OF THE INVENTION

Outline of the System

The portable viewing/listening system described in the followingembodiments is constituted by a main device which is fixedly orsemi-fixedly installed in a house and an easy-to-carry portableplaying-back device (hereinafter, referred to as a portable device). Themain device includes at least a function of receiving (in some cases, afunction of playing-back is included) program data that is providedthrough broadcasting (both broadcast transmitted over radio waves, andbroadcast transmitted through a cable transmission path are included), afunction of internally storing the received program data, and a functionof online-transferring or offline-transferring the stored program datato the portable device. To online-transfer any selected program data,the portable device is connected to the main device. The portable devicethen internally stores the program data that is transferred from themain device, and plays-back the stored program data at the users'convenience. On the other hand, to offline-transfer the program data,the main device once writes the internally stored program data to arecording medium (video tape, rewritable optical disk, solid memorycard, and the like). After the writing, the recording medium is detachedfrom the main device and is then attached to the portable device.Accordingly, in this case, the portable device reads any desirableprogram data from the attached recording medium and then plays-back thesame.

A distinctive characteristic of the system of the present invention liesin a method of transferring data from the main device to the portabledevice. Specifically, this system discretely transfers data from themain device to the portable device. As described in the foregoing, oneprogram data is generally constituted by a plurality of programcomponents (video, audio, closed caption, for example). As these programcomponents are being concurrently played-back, the program componentsare conventionally transferred to the portable device at one time. Onthe other hand, in this system, every program component constituting oneprogram data is assigned a transfer priority so as to be discretelytransferred in the direction of a time axis according to the given orderof priorities.

With such data transfer being discretely executed, some of the programcomponents may possibly be entirely transferred to the portable deviceeven if data transfer from the main device to the portable device isdiscontinued in a short time (i.e., prematurely). Therefore, the userscan enjoy the entire program, albeit incomplete, by playing-back thealready-transferred program components. In the aforementionedconventional portable viewing/listening system, however, none of theprogram components of the program data is entirely transferred if datatransfer to the portable device is discontinued in a short time. As aresult, the users cannot enjoy the entire program.

First Embodiment

FIG. 1 is a block diagram showing the structure of a portableviewing/listening system according to a first embodiment of the presentinvention. In FIG. 1, the portable viewing/listening system of the firstembodiment includes a main device 1 and a portable device 2. Theportable device 2 is detachable/attachable from/to the main device 1.

The main device 1 includes an antenna 101, a receiving part 102, ademultiplexing part 103, an additional information generating part 104,a storage information generating part 105, a storage managing part 106,a storage part 107, a connection interface 109, a user input-output part110, a decoder 111, a memory 112, and a CPU 113.

The receiving part 102 includes a tuner and a demodulator which areconstituents of a typical digital broadcast receiver. The receiving part102 receives a broadcast wave that is received by the antenna 101, andoutputs a digital stream. Video information, audio information,additional information and the like are multiplexed into the digitalstream. A specific format for the digital stream may be MPEG-2 TS(Transport Stream), for example. Note that MPEG-2 TS, and multiplexingby MPEG-2 TS are standardized by the international standard of MPEG-2Systems.

The demultiplexing part 103 is constituted by a TS processor, forexample, and separates the digital stream that is outputted from thereceiving part 102 into the video information, the audio information,the additional information, and the like. When the digital stream isMPEG-2 TS, the demultiplexing part 103 classifies TS packets being thesmallest unit of the digital stream according to values of packet ID(pid) which are written in TS packet headers so as to separate themultiplexed video information, audio information, additionalinformation, and the like.

The additional information generating part 104 receives information thatis relevant to the additional information from among the informationthat is included in the digital stream which is separated by thedemultiplexing part 103 so as to generate additional information. Aformat for the additional information is a section format defined inDVB-SI being the international standard, for example. In DVB-SI, amethod of transmitting information which is relevant to a broadcastchannel (pid, for example) and information which is relevant to an EPG(Electric Program Guide) is defined as a data format based on thesection format. The information relevant to the EPG, for example, istransmitted in the section format called EIT (Event Information Table).To transmit information in the section format, information to betransmitted is divided into a certain size or smaller, and is repeatedlytransmitted. In this manner, the additional information generating part104 collects and merges the divided information into one data, andupdates the information if the contents thereof have been changed.

The storage information generating part 105 converts the videoinformation and audio information that are inputted from thedemultiplexing part 103 into a format which is suitable for storing inthe storage part 107, and then outputs the converted information to thestorage managing part 106. The storage information generating part 105also generates both detailed video information and non-detailed videoinformation in accordance with the video information that is inputtedfrom the demultiplexing part 103 as is required. The non-detailed videoinformation is of inferior image quality to the detailed videoinformation but has a smaller amount of data. Accordingly, thenon-detailed video information is done with a transfer processing thatis quicker than the detailed video information.

Both detailed video information and non-detailed video information aregenerated in the storage information generating part 105 in a first casewhere the CPU 113 instructs the storage information generating part 105to generate the non-detailed video information. If this is the case, thestorage information generating part 105 outputs the video informationthat is inputted from the demultiplexing part 103 as detailed videoinformation in its current form. Further, the storage informationgenerating part 105 changes the resolution of the video information thatis inputted from the demultiplexing part 103 or intermittently decimatesframes thereof so as to generate and output the non-detailed videoinformation.

Both detailed video information and non-detailed video information aregenerated in the storage information generating part 105 in a secondcase where the video information that is inputted from thedemultiplexing part 103 includes the non-detailed video information aswell as the detailed video information from the beginning. There may bea case where the received video information is hierarchically encoded ora case where the received video information is transmitted in ahierarchical transmission mode, for example. If this is the case, thevideo information that is inputted from the demultiplexing part 103 ismulti-layered in varying image qualities, and the upper layer has themore codes and the better image. In this manner, the storage informationgenerating part 105 outputs the video information that is included inthe top layer as detailed video information without any change. Further,the storage information generating part 105 outputs the videoinformation that is included in the lower layer as non-detailed videoinformation. To generate video information corresponding to therespective layers, a method of selecting layers which is used in thetypical digital broadcast receiver can be used as it is.

The storage information generating part 105 outputs the aforementionednon-detailed video information to the storage managing part 106 as videoinformation for a digest video. Accordingly, the CPU 113 manages thenon-detailed information which is stored in the storage part 107 as thevideo information for the digest video. Note that, in the firstembodiment, the detailed information and non-detailed information aregenerated only for video. However, the detailed information andnon-detailed information may be generated for audio as well depending onthe particular situation.

The storage managing part 106 and the storage part 107 areinterconnected, and the storage managing part 106 controls informationwriting and reading with respect to the storage part 107 under thecontrol of the CPU 113. The storage part 107 is constituted by arelatively large-capacity storage device using a hard disk or DVD-RAM,for example. The storage part 107 stores program data.

The connection interface 109 is used to physically and electricallyconnect the main device 1 to other devices, and to transmit video, audioor other digital information from/to the other devices. Such aconnection interface 109 may be a typical input-output interface fordigital information including an interface of IEEE1394.

The user input-output part 110 receives inputs from the users orpresents the users in which state the device is. Such a userinput-output part 110 is exemplarily constituted by an infrared remotecontroller, remote control photoreceiving part, pilot lamp, and thelike. Information is presented to the users also through a GUI operationutilizing OSD (On Screen Display) that is included in the videoinformation outputted from the decoder 111. In this case, the users pushbuttons which are provided for the remote controller while observing theOSD, for example, so as to play-back or erase stored programs, orpreselect or transfer programs.

The memory 112 stores various information relating to the operation ofthe main device 1. To be more specific, the memory 112 stores programinformation that is used to execute operation control of the main device1, additional information that is outputted from the additionalinformation generating part 104, and storage management information thatis used to manage the information stored in the storage part 107, forexample.

The CPU 113 and other constituents which are provided in the main device1 are interconnected, and the CPU 113 executes the program informationthat is stored in the memory 112 so as to collectively control thoseconstituents.

The portable device 2 includes a connection interface 201, a portableviewing/listening information managing part 202, a storage part 203, adecoder 204, a display 205, a speaker 206, a user input-output part 207,a memory 208, and a CPU 209.

The connection interface 201 is physically and electrically connected tothe connection interface 109 in the main device 1, and is used toreceive video, audio and other digital information from the main device1. Such a connection interface 201 may be a typical input-outputinterface for digital information including the interface of IEEE1394.

The portable viewing/listening information managing part 202 and thestorage part 203 are interconnected. The storage part 203 is constitutedby a storage device using a hard disk, DVD-RAM, or solid memory, forexample. Since the storage part 203 is installed in the portable device2, it is preferred that the storage part 203 be downsized. The storagepart 203 stores program data to be transferred from the main device 1.

The decoder 204 receives and decodes the program data which is stored inthe storage part 203 so as to convert the data into analog video/audiosignals. The display 205 is constituted by a liquid crystal display or asmall-sized CRT display, for example, and receives the analog videosignals that are outputted from the decoder 204 so as to display thecorresponding image thereon. The speaker 206 receives the analog audiosignals that are outputted from the decoder 204 so as to output thecorresponding audio therefrom.

The user input-output part 207 receives inputs from the users, andpresents the users in which state the device is. Such a userinput-output part 110 is exemplarily constituted by an infrared remotecontroller, remote control photoreceiving part, pilot lamp, and thelike. Information is also presented to the users through the GUIoperation utilizing an OSD which is displayed on the display 205. Inthis case, the users push buttons which are provided for the remotecontroller while observing the OSD, for example, so as to set toplay-back or erase stored programs, or preselect or transfer programs.

The memory 208 stores various information that is relevant to anoperation of the portable device 2. In detail, the memory 208 storesprogram information which is used to execute operation control of theportable device 2, storage management information which is used tomanage the information stored in the storage part 203, and the like.

The CPU 209 and other constituents in the portable device 2 areinterconnected, and the CPU 209 executes the program information whichis stored in the memory 208 so as to collectively control theseconstituents.

FIG. 2 is a diagram exemplarily showing the structure of a storage listto be stored in the memory 112 of the main device 1. This storage listis data for managing the program data which is stored in the storagepart 107 of the main device 1, and is tablestructured. Specifically,each line of the table represents a single program component for aparticular program. The storage list of FIG. 2 exemplarily shows thatthe storage part 107 stores eight program components in total. Each lineof the table includes four attributes of event_id, type, size, andtransfer priority.

The attribute “event_id” is attribute information for identifying theprograms. In this example, for the sake of simplicity, event_id for theProgram 1, Program 2 and Program 3 are assumed to be 0x0001, 0x0002,0x0003, respectively. Herein, “0x” indicates that a hexadecimal digitalfollows.

The attribute “type” is attribute information for single programcomponent for identifying the types of program components. Characters“C”, “A”, and “V” which are found in the storage list of FIG. 2respectively represent Closed Caption, Audio and Video. Digest videorepresented by “D” is further included therein. This will be describedlater.

The attribute “size” indicates a size of the area in the storage part107 that is occupied by the corresponding program component. A size unitherein may simply be a bite, or a block which is represented by thenumber of blocks in a given size.

The attribute “transfer priority” is attribute information which is usedto determine in which order the program components are transferred whenthe program data is transferred from the main device 1 to the portabledevice 2. In this example, the smaller value has the higher priority.

Among the attributes in FIG. 2, when the program is received, event_id,type and size can be obtained from the information that is transmittedas additional information for the program. The transfer priorities areestablished when the transfer processing of at least one program isexecuted.

FIG. 3 is a flowchart illustrating an operation which is executed on themain device side when the program data is transferred from the maindevice 1 to the portable device 2 in the portable viewing/listeningsystem of the first embodiment. The processing of FIG. 3 is realizedwhen the CPU 113 in the main device 1 executes the program informationwhich is stored in the memory 112 in the main device 1. Hereinafter, byreferring to FIG. 3, the operation whereby the main device 1 transfersthe program data to the portable device 2 is described.

First, the CPU 113 selects a first program from among the programs whichare stored in the storage part 107 (step S1O1). The storage list (seeFIG. 2) which is stored in the memory 112 is referred to so as to knowwhat programs are stored in the storage part 107. Taking the storagelist of FIG. 2 as an example, “Program 1” is the program to be selectedfirst from the stored data of the Program 1, Program 2, and Program 3.Thereafter, the CPU 113 judges whether or not any program was selectedin step S101 (step 5102). In this example, since “Program 1” wasselected in step 5101, the CPU 113 goes to step S103.

In step S103, the CPU 113 sets transfer priorities for each programcomponent constituting the program that is selected in step S101. Fordetails of this subroutine step S103, see FIG. 4.

By referring to FIG. 4, the CPU 113 sequentially selects the programcomponents constituting the target program (first “Program 1” in thisexample) that is selected in step S101 (step S201). Thereafter, the CPU113 judges whether or not any program component was selected in stepS201 (step S202). If yes, the CPU 113 provides the program componentthat is selected in step S201 with an applicable default value which ispredetermined for every type of program components as a transferpriority (step S203).

FIG. 5 shows a transfer priority table in which the default valuesindicating the transfer priorities for each type of the programcomponents are defined. The transfer priority table of FIG. 5 is storedin the memory 112, for example. In FIG. 5, as an example, the defaultvalues of 1, 2, 3 and 4 as transfer priorities are respectively assignedto the types C, A, D and V. The transfer priority table of FIG. 5 has aclass which is defined for each type. The class herein shows theclassified types of program components. Preferably, data that isreplaceable with each other is classified into the same class. Forexample, audio can be replaced by closed caption, and detailed video canbe replaced by digest video. In step S203, the CPU 113 first refers tothe transfer priority table of FIG. 5, and then sets transfer prioritiesby default for every program component in the storage list of FIG. 2.

After step S203 is performed, the CPU 113 returns to step S201 andselects the next program component for the target program. Thereafter,the CPU 113 assigns a transfer priority for the selected programcomponent by referring to the transfer priority table of FIG. 5 (stepS203).

After steps S201 to S203 are repeated, and after each program componentconstituting the target program is assigned a transfer priority, theprogram components to be selected in step S201 would have all been goneby then. Therefore, the CPU 113 determines that no program component wasselected in step S202, and advances to step S204.

In step S204, the CPU 113 selects the classes that are defined in thetransfer priority table of FIG. 5 in the given order. In this example,two classes of “script” and “display” are defined in the transferpriority table of FIG. 5. Accordingly, in step S204, either one of the“script” or “display” is initially selected, the other one is selectedsecond, and a third selection results in no class being selected.Thereafter, the CPU 113 judges whether or not any class was selected instep S204 (step 5205). If yes, the CPU 113 then judges whether or notthe program component that is defined in the selected class as being atop transfer priority is included in the target program (step S206). Byreferring to the transfer priority table in FIG. 5, for example, one ofthe program components which is classified in the class of “script” isin type “C” with a transfer priority of “1”, and the other programcomponent is in type “A” with a transfer priority of “2”. It means, inthe class of “script”, the program component in type “C” is defined asbeing the top priority. Similarly, as to the program components whichare classified in the class of “display”, the program component in type“D” is assigned with a transfer priority of “3”, and thus is defined asbeing the top priority in the class of “display”. Therefore, accordingto the definition of the transfer priority table of FIG. 5, in stepS206, the CPU 113 judges whether or not the target program includes anyprogram component in type “C” when the currently selected class is“script”. On the other hand, when the currently selected class is“display”, the CPU 113 judges whether or not the target program includesany program component in type “D”.

When the target program has no program component which is defined asbeing the top transfer priority in the selected class, the CPU 113selects any program component having the highest transfer priority nextto the top priority, and updates the priority value thereof to a valuewhich is defined as being the top priority in the class (step S207). Ina case where the class of “script” is currently selected and eachprogram component that is included in the target program is in type “A”,the transfer priority for the program component in type “A” is updatedfrom the default value of “2” to “1”, which is defined as being the toppriority in the class. Similarly, in a case where the class of “display”is currently selected and each program component that is included in thetarget program is in type “V”, the transfer priority for the programcomponent in type “V” is updated from the default value of “4” to “3”,which is defined as being the top priority in the class. Each update instep S207 is reflected in the storage list of FIG. 2. That is, anyapplicable transfer priority for the program component in the storagelist is updated. Thereafter, the CPU 113 returns to step S204. Notethat, when the target program has any program component which is definedas being the top transfer priority in the selected class, the CPU 113returns to step S204 without updating any transfer priority.

Next, the CPU 113 selects the next class from the transfer prioritytable of FIG. 5, refers to the transfer priority that is defined for therespective types in the selected class, and judges whether or notdefault transfer priorities for each program component that is includedin the target program should be updated. If yes, the CPU 113 updates theapplicable values to the predetermined ones.

After steps S205 to S207 are repeated, and after the processing is donewith every class, the classes to be selected in step S204 would have allbeen gone by then. Thus, the CPU 113 determines that no class wasselected in step S205, terminates the subroutine processing in FIG. 4,and then returns to the main routine processing in FIG. 3.

Referring back to FIG. 3, the CPU 113 selects the next program from thestorage list of FIG. 2 (step S101), and assigns transfer priorities foreach program component constituting the selected program (step S103).After steps S101 to S103 are repeated, and after every program in thestorage list is assigned a transfer priority, the CPU 113 judges thatthere is no program to select next (step S102), and then advances tostep S104.

In step S104, the CPU 113 initially sets a count value N of a counterwhich indicates a transfer priority (hereinafter, refers to as transferpriority counter) to a value of “1” indicating the top transfer priority(step S104). Then, the CPU 113 judges whether or not the count value Nof the transfer priority counter is 5 (step S105). Herein, four valuesof 1, 2, 3 and 4 are available as transfer priorities in the transferpriority table in FIG. 5. Therefore, if N=5, it means that everytransfer priority is completely assigned. Since N=1 at the beginning,the CPU 113 determines that N≠5, and then advances to step S106.

In step S106, the CPU 113 selects one program component whose transferpriority is N (at the beginning, N=1) from the storage list of FIG. 2.Thereafter, the CPU 113 judges whether or not any program component wasselected in step S106 (step S107). If yes, the CPU 113 takes out theattribute information of “event_id”, “type”, and “size” from the line ofthe storage list corresponding to the program component which isselected in step S106, and then transfers the same to the portabledevice 2 (step S108). Then, the CPU 113 takes out main data of theprogram component which is selected in step S106, and transmits the sameto the portable device 2 (step S109). Thereafter, the CPU 113 returns tostep S106, selects another program component whose transfer priority isN from the storage list of FIG. 2, and then executes the transferprocessing for the selected program component.

After steps S106 to S109 are repeated, and after each program componenthaving the transfer priority of N is completely transferred, the CPU 113judges that all the program components to be selected in step S106 aregone (step S107), increments the count value N of the transfer prioritycounter by 1 (step S110), and then returns to step S105. Then, the CPU113 executes the transfer processing for the program component havingthe transfer priority of N (N=2) after the count value N of the transferpriority counter is updated.

After steps S105 to S109 are repeated, and after the transfer processingis done with every program component having the transfer priorities of 1to 4, N=5. Thus, the CPU 113 judges that the transfer processing iscompletely done in step S105, and then terminates the processing.

FIG. 6 shows the structure of a receipt list which is to be stored inthe memory 208 in the portable device 2. The receipt list is data thatis used to manage how the data which is stored in the storage part 203in the portable device 2 (that is, program data that is transmitted fromthe main device 1) is stored, and is table-structured. The lines of thetable are in a one-to-one correspondence with the program componentsthat are stored in the storage part 203. Also, each line of the tablehas six attributes including receipt order, off set, size, event_id,type, and length of play-back time.

The attribute “receipt order” indicates the order in which the portabledevice 2 receives the data of the program components from the maindevice 1, and a value does not appear more than once in the receiptlist. Thus, the receipt order can be used as a key for specifying linesof the receipt list.

The attribute “offset” indicates where the program components being inthe one-to-one correspondence with the lines of the receipt list arelocated in the data that is received from the main device 1. Whentransfer of the entire program from the main device 1 to the portabledevice 2 is presumably considered a bit stream or a file, the attribute“offset” represents the number of bites from the beginning of thetransfer. The value of the offset can be represented simply in a bite orthe number of blocks in a given size similar to the case where theattribute “size” in the storage list of FIG. 2 matters.

The attribute “size” represents a size of an area in the storage part203 of the portable device 2 which is occupied by the program componentsbeing in the one-to-one correspondence with the lines of the receiptlist. The attribute “size” is also represented in a similar unit to theattribute “offset”.

The attribute “event_id” is attribute information that is used toidentify to which program the program components being in the one-to-onecorrespondence with the lines of the receipt list respectively belong.

The attribute “type” is attribute information that is used to identifythe types of the program components being in the one-to-onecorrespondence with the lines of the receipt list.

The attribute “length of play-back time” represents the length ofplay-back time when the program components being in the one-to-onecorrespondence with the lines of the receipt lines are played-back underthe same conditions. When data transfer is interrupted halfway throughfor some reason, the number of bites of the transferred data is lessthan the number of bites of the same program component which isbroadcast. In such a case, the length of play-back time is assigned alength of time corresponding to the transferred data.

FIG. 7 is a flowchart illustrating how the portable device 2 is operatedto receive program data that is transmitted from the main device 1 inthe portable viewing/listening system of the first embodiment. Theprocessing in FIG. 7 can be realized when the CPU 209 in the portabledevice 2 executes program information which is stored in the memory 208in the portable device 2. Through the processing, the program data thatis transmitted from the main device 1 is stored in the portable device2, and the receipt list of FIG. 6 is also generated. Hereinafter,referring to FIG. 7, how the portable device 2 is operated to receivethe program data transmitted from the main device 1 will be described.

First of all, the CPU 209 initializes the receipt list of FIG. 6 (stepS301). The easiest way of initializing the receipt list is done bydeleting every line thereof and, at the same time, deleting the programdata that is stored in the storage part 203 in the portable device 2.Thereafter, the CPU 209 assigns a value of 0 to a variablecurrent_offset, and assigns a value of 1 to a variable send_count (stepS302). Then, the CPU 209 receives the attribute information of “size”,“event_id”, and “type” to be transmitted from the main device 1 (stepS303). Such attribute information is the one that is transmitted in stepS108 in FIG. 3. The CPU 209 then judges whether or not there is any datato receive in step S303 (step S304). If not, the CPU 209 terminates theoperation, but if yes, the CPU 209 then judges whether or not anavailable region of the storage part 203 is sufficiently large for thevalue of the “size” which is obtained in step S303 (step S305). If yes,the CPU 209 goes to step S306, but if not, the CPU 209 returns to stepS303.

In step S306, the CPU 209 adds a line to the receipt list of FIG. 6, andthen assigns values which are obtained in step S303 to eachcorresponding attribute “size”, “event_id”, or “type” in the added line.Thereafter, the CPU 209 assigns the value of the variable current_offsetto the attribute “offset” in the added line (step S307). The CPU 209adds the value of “size” which is obtained in step S303 to the variablecurrent_offset (step S308), and then assigns the value of the variablesend_count to the attribute “receipt order” in the added line (stepS309). The CPU 209 then increments the value of the variable send_countby 1 (step 5310). After performing step S310, the CPU 209 receives themain data of the program components that are transmitted from the maindevice 1, and then stores the same in the storage part 203 (step S311).Then, the CPU 209 sets the attribute “length of play-back time” (stepS312). Herein, it is assumed that the main data of the programcomponents itself includes, as additional information, a bit rate valueindicating the number of data bit per unit presentation time. In thiscase, to convert the value of the “size” which is obtained in step S303to the length of play-back time, the value of the “size” is divided bythe bit rate that is obtained in the aforementioned manner. Note that,the value of the length of program time can be notified directly fromthe main device 1 as data as in the case with the “size”, for example.Next, the CPU 209 judges whether or not a receipt of program data isdiscontinued halfway through for some reason (step S313). If yes, theCPU 209 advances to step S314, but if no, the CPU 209 returns to stepS303. Such discontinuation may include a case, for example, where theusers abruptly disconnect the portable device 2 from the main device 1,and vice versa.

In step S314, the CPU 209 finds a value of the attribute “size” in thereceipt list from the size of the program component which is actuallystored in the storage part 203, and resets the value (step S314). Then,the CPU 209 obtains, in a similar manner to step S312, a value for thelength of play-back time from the value of the attribute “size” in thereceipt list, and then resets the “length of play-back time” in thereceipt list (step S315). Then, the CPU 209 terminates the processingfor receiving.

FIG. 8 is a flowchart illustrating how the portable device 2 is operatedto play-back the program. This processing can be realized when the CPU209 executes the program information which is stored in the memory 208in the portable device 2. Hereinafter, by referring to FIG. 8, how theportable device 2 is operated to play-back the program will bedescribed.

First, a description of a class table that is used to play-back theprogram is as follows. FIG. 9 is an exemplary class table. The classtable is, for example, stored in the memory 208, and the CPU 209 is atliberty to access the class table. As shown in FIG. 9, lines of theclass table are in a one-to-one correspondence with the types of theprogram components, and each line has three attributes of “type”,“class”, and “presentation priority”.

In FIG. 9, the attribute “class” shows the classified types of theprogram components. By taking this class table as an example, twoclasses of “script” and “display” are defined therein. The first andsecond lines thereof show that closed caption and audio are instancesbelonging to the same class of “script”, and the third and fourth linesthereof show that digest video and detailed video are instancesbelonging to the same class of “display”. The attribute “presentationpriority” defines in which order the program components in varying typesclassified into the same class should be presented to the users. In thisexample, the smaller value has the higher presentation priority. Suchclass table is referred to to search for some other program componentsfor replacement when the program component being played-back isinterrupted halfway.

By referring to FIG. 8, the CPU 209 first executes displaying andselecting operation of the programs (step S401). To be more specific,the CPU 209 generates a list of the programs stored in the storage part203 by referring to the receipt list of FIG. 6, and then displays thegenerated list on the display 205. Thereafter, the CPU 209 let the usersselect any program which is desired to be played-back from the displayedlist. The selection of the programs is done through the userinput-output part 207. When it is desired for the list of the programsdisplayed on the display 205 to include titles of the programs as well,data indicating the title-to-“event_id” relationship may be sent alongwith the titles during transmission of the program data from the maindevice 1 to the portable device 2. For such data indicating therelationship, additional information to be transmitted throughbroadcasting for the EPG (Electric Program Guide) may be used. Next, theCPU 209 extracts, from the receipt list, each program component of theprogram which is selected in step S401 to be played-back (step S402).Thereafter, the CPU 209 generates a list of the program componentsconstituting the selected program according to the extraction result instep S402, and then displays the generated list on the display 205 (stepS403). In response thereto, the users select one or more programcomponent (s) to be played-back from the displayed list. The selectionof the program components is done through the user input-output part207. Then, the CPU 209 makes a preparation for concurrent play-back ofall of the program components which are selected in step S403 (stepS404). By concurrently playing-back the program components, lip synchcan be attained, for example, which is synchronization between aspeaker's lip movements in the video and audio.

Thereafter, the CPU 209 executes a play-back processing of the programcomponents which are prepared in step S404 (step S405). The CPU 209 thenjudges whether or not any play-back position of the program componentsbeing played-back has reached to a tail (end) of the data (step S406).There may be a case where the data is completely played-back, or a casewhere the data is interrupted. If none of the play-back positions of theprogram components has reached to the tail, the CPU 209 returns to stepS405 so as to continue the play-back processing. On the other hand, ifany play-back position of the program components has reached to thetail, the CPU advances to step S407.

In step S407, the CPU 209 selects any other program component in thesame class as the program component whose play-back position has reachedto the data tail but in different type in the order of presentationpriorities that are defined in the class table of FIG. 9. To be morespecific, the CPU 209 first extracts every program componentconstituting the program that is being played-back from the receipt listof FIG. 6, and then selects, from among the extracted programcomponents, any program component belonging to the same class as theprogram component whose play-back position is judged to have reached tothe data tail in step S406. Thereafter, the CPU 209 takes out anyprogram component, from among the selected program components, whosepresentation priority is lower than the one whose play-back position hasreached to the data tail, and then selects the type of the programcomponent whose presentation priority is the highest from among thetaken-out program components. When the play-back position of the programcomponent in type “V” presumably reaches to the data tail duringplay-back, the CPU 209 selects the type “D”, which is in the same classof “display” as the type “V” and which has the presentation prioritylower than the type “V” but the highest among the rest.

Thereafter, the CPU 209 judges whether or not any type is selected instep S407 (step S408). If yes, the CPU 209 then judges whether or notthe program component in the type which is selected in step S407 isalready being played-back (step S409). This first embodiment takes astructure where the users can simultaneously select, in step S403, aplurality of program components in varying types which are classifiedinto the same class. Therefore, the program component in the type whichis selected in step S407 may possibly be already being played-back. Forexample, if the play-back position of the program component in type “V”reaches to the data tail when the program components in type “D” and “V”are concurrently being played-back, the data of the program component intype “D” is selected instep S407 as described above. In such a case, theCPU 209 returns to step S405 so as not to repeatedly play-back theprogram component in the same type, and thus does not replace theinterrupted program component with others to be played-back. On theother hand, if the program component in the type which is selected instep S407 is not yet played-back, the CPU 209 replaces the interruptedprogram component with the program component in the selected type to beplayed-back (step S410). In this case, the CPU 209 does not startplaying-back from the beginning of the program component in the typeselected in step S407. Instead, the CPU 209 starts playing-back from thecontinued part of the interrupted program component. In this example,closed caption and audio are in the same class. Even if the data ofaudio is interrupted, closed caption thus may take the place by beingplaying-back from the interrupted part. In this manner, the users canenjoy the program not with audio but with closed captions. Thereafter,the CPU 209 returns to step S405.

On the other hand, when no type was selected in step S408, the CPU 209determines that there is no more component to replace to play-back, andthen terminates the play-back processing for the class (step S411). Thismay happen when the users have selected the type having the lowestpresentation priority. Also, this may happen when the target program iscompletely played-back. At this time, the CPU 209 changes a value of aflag variable indicating the play-back processing being executed on theclass basis into a value indicating the processing being terminated.Then, the CPU 209 judges whether or not the program component beingplayed-back is completely played-back. This judgement is made byreferring to the value of the aforementioned flag variable. If anyprogram component is still being played-back in whatever the class, theCPU 209 returns to step S405 so as to continue the play-back processingfor other classes. On the other hand, if the target program iscompletely played-back, the program components being played-back in eachclass are terminated. Thus, the CPU 209 terminates the play-backprocessing of the program.

FIG. 10 is a diagram illustrating how data is transferred in theportable viewing/listening system of FIG. 1. Hereinafter, how data istransferred in the portable viewing/listening system of FIG. 1 will bedescribed in detail.

FIG. 10( a) shows a time transition of data constituting the program tobe broadcast. In FIG. 10( a), a lateral axis indicates a lapse of timeduring broadcast, and a vertical axis indicates a bit rate duringbroadcast, respectively. In detail, FIG. 10( a) shows that the Program 1is broadcast between Time t0 and Time t1, the Program 2 is broadcastbetween Time t1 and Time t2, and the Program 3 is broadcast between Timet2 and Time t3, respectively. Further, the Program 1, Program 2, andProgram 3 are respectively provided with audio, closed caption, andvideo as a program component (mono-media constituting the program). Forthe sake of simplicity, the length of broadcast time for the Program 2(t2−t1) and the length of broadcast time for the Program 3 (t3−t2) areequal, and the length of broadcast time of the Program 1 (t1−t0) isexactly twice the length of broadcast time for the Program 2 (or Program3). Further, a bit rate for the respective program components remainsinvariant no matter which program, and thus, a ratio among a bit rate ofclosed caption bc, a bit rate of audio ba, and a bit rate of video bv isalways 1:2:4.

FIG. 10( b) shows a time transition which takes place when program datais transferred from the main device 1 to the portable device 2. In FIG.10( b), a lateral axis indicates a lapse of time for a data transferoperation, and a vertical axis indicates a bit rate during transfer,respectively. It is assumed that transfer is started at Time t4 as inthe conventional system shown in FIG. 18( b). As the total number ofbits to be transferred is equal to the example in FIG. 18, the data iscompletely transferred at Time t9 as is in the conventional system. InFIG. 10( b), each closed caption part of the programs to be transferred(Program 1, Program 2, and Program 3) is first transferred between Timet4 to Time t5, each audio part thereof is then transferred between Timet5 to Time t6, and lastly each video part thereof is transferred betweenTime t6 to Time t9. As described above, the rate among the programcomponents of closed caption, audio, and video during broadcast is1:2:4. Therefore, the length of time which is taken to transfer closedcaption of the programs (t5−t4), the length of time which is taken totransfer audio thereof (t6−t5), and the length of time which is taken totransfer video thereof (t9−t6) are respectively expressed by thefollowing equations (1), (2) and (3).(t5−t4)=(t9−t4)×{1/(1+2+4)}  (1)(t6−t5)=(t9−t4)×{2/(1+2+4)}  (2)(t9−t6)=(t9−t4)×{4/(1+2+4)}  (3)

Further, t6 can be represented by the following equation (4).t6=t4+[(t9−t4)×{(1+2)/(1+2+4)}]  (4)

FIG. 10( c) shows, in the portable viewing/listening system in FIG. 1, acase where the transfer of program data is interrupted at Time ta. Inthis example, Time to presumably satisfies t6<to<t9. Even if thetransfer of the program data is discontinued halfway through at Time ta,audio components and closed caption components for the respectiveprograms are completely transferred by then. At this stage, in theportable device, the programs are not available in video but in closedcaption and audio. This means that the users can be informed of thecontents thereof to some extent. In other words, the users can enjoyevery program with closed caption and audio, although not with video. Ina practical sense, the bit rates of the closed caption and audio arerather high as compared to bit rates of the video. In this sense, Timet6 when every closed caption component and audio component arecompletely transferred possibly comes at much earlier timing than Time 9when the program is entirely transferred with the video components. Inparticular, the length of time which is required for transferring thevideo (t9−t6) is rather long as compared to the length of time which isfor transferring the closed caption components and the audio components(t6−t4). Therefore, the audio components may highly-possibly be entirelytransferred even if transfer is stopped in a rather short time. Further,as is transferred in text, the bit rate of the closed caption componentscan be lowered to a greater extent than the bit rate of the audiocomponents. Therefore, transfer of the closed caption components can becompleted much quicker than the transfer of the audio components.

FIG. 11 shows a time transition which takes place to transfer theprogram in a case where data to be transferred includes a digest videoin the portable viewing/listening system in FIG. 1. The case herein issomewhat complicated as compared to the case in FIG. 10.

FIG. 11( a) shows a time transition for information of the program to bebroadcast. This example herein is different from the example in FIG. 10(a) in that the Program 1 includes a digest video D1 in a detailed videoV1, and the Program 2 does not include a closed caption C2. The bit ratewithout the closed caption C2 is assigned to a detailed video V2, andthus, the detailed video V2 is increased by the closed caption C2 asmuch as the other programs.

FIG. 11( b) shows a time transition which takes place when the programis transferred. First of all, by taking transfer started at Time t4 asan example, information that is sufficient to play-back every program tosome extent is transferred by Time t10. This means that closed captionis transferred to the Programs 1 and 3, and audio is transferred to theProgram 2. Note that the program components to be transferred betweenTime t4 to Time 10 are the ones having the transfer priority of 1 in thestorage list of FIG. 12.

Thereafter, the program components in the “script” class which are nottransferred before the lapse of Time t10 are transferred between Timet10 to Time t11. By being completely transferred by Time t10, the audioof the Program 2 is not transferred at this stage. The programcomponents to be transferred between Time t10 to Time t11 are the oneshaving the transfer priority of 2 in the storage list of FIG. 12.

After Time t11, video begins to be transferred. First of all, the digestvideo D1 of the Program 1 is transferred. The digest video is equal tothe detailed video in the sense but has less information. Having lessinformation means a state, for example, in which on-screen resolution islow or time-axis resolution is low, for example, a frame in a fewseconds.

When encoding of the detailed video is hierarchical encoding such asresolution scalability defined in MPEG-2 Video, for example, wherevideos in a plurality of layers are included in codes, data of thedigest video can be obtained by selectively extracting the codes in aparticular layer. Further, encoding by a hierarchical transfer methodcan be done in a similar manner to the hierarchical encoding.Alternately, in a case where a scene being a part on the time-axis ofthe program is specified by program index codes which are adopted in thedigital broadcasting system in Japan, only the video in one or morescenes that is specified by the index as being more important can betaken out as the digest video. In this case, the remaining scenes do nothave video data. However, by displaying the last frame having the videodata or by blacking out, it can be regarded as one program component inseries.

The videos are transferred between Time t11 and Time t12. In detail, thedetailed video is transferred to the Programs 2 and 3, and the digestvideo being similar to the detailed video in the sense but having lessinformation is transferred to the Program 1. The videos become availableto some extent for every program at Time t12. The program components tobe transferred between Time t11 and Time T12 are the ones having thetransfer priority of 3 in the storage list of FIG. 12.

Lastly, the detailed video V1 of the Program 1 beings to be transferredfrom Time t12. For the transfer that is started from Time t12, theprogram components having the transfer priority of 4 in the storage listof FIG. 12 are transferred. It is herein assumed that the detailed videoV1 of the Program 1 was supposed to be completely transferred by Timet13 but was interrupted at Time tb exactly at the halfway between Timet12 and Time t13. If this is the case, as to the program components inthe “display” class of the Program 1, the digest video is whollytransferred but the detailed video is only half-transferred, i.e., onlythe first-half of the detailed video is transferred. Even if datatransfer is interrupted due to such eventuality, the users can enjoy theprogram with video to some extent because the video information isalready provided to every program to some extent. Further, even if thedata transfer is interrupted at an earlier stage, the users can enjoythe program with closed caption (additionally, audio).

FIG. 12 is an exemplary storage list which is to be generated in a casewhere the received data includes a digest video in the main device 1 ofFIG. 1. In FIG. 12, the Program 1 has the digest video in the programcomponent (the third line of the storage list; in the receipt list, thesixth program component to be received). Accordingly, in the processingdescribed in FIG. 4 where transfer priorities are determined (stepS206), there is a digest video having the top transfer priority which isdefined for the “display” class. Consequently, the processing of stepS207 which re-writes the transfer priorities is not executed. Therefore,the digest video “D” and the detailed video “V”, both of which are thetypes of the program components which are classified into the “display”class, are set to the transfer priorities by default. Further, as theProgram 2 does not have closed caption having the top transfer prioritydefined for the “script” class, by step S207, the transfer priority ofaudio “A” is changed into the value of 1 which is defined as being thetop priority for the “script” class.

FIG. 13 is an exemplary receipt list which is to be generated when thedata that is transferred from the main device 1 to the portable device 2of FIG. 1 includes a digest video. In FIG. 13, as to the Program 1, theportable device 2 receives the entire digest video of 30 minutes, butreceives only the first-half of the detailed video of 15 minutes. Inthis manner, in step S406, the detailed video reaches to the tail ofdata 15 minutes after the start of play-back of the detailed video andaudio in the play-back processing of the program described in FIG. 8(step S405). Thereafter, the digest video being the program component inthe “display” class after the lapse of 15 minutes is found in step S407,and then is stated to be played-back as a replacement for the detailedvideo in step S410. The play-back image of the Program 1 is accordinglylowered in quality after the lapse of 15 minutes from the start, but, isstill sufficient for the users to enjoy the program.

Second Embodiment

FIG. 14 is an outer perspective diagram showing the physical structureof a portable viewing/listening system according to a second embodimentof the present invention. Further, FIG. 15 is a block diagram showingthe electrical structure of the portable viewing/listening systemaccording to the second embodiment of the present invention. Byreferring to FIGS. 14 and 15, the main device 1 includes a processingpart 1 a, a charging part 1 b, and a cradle-type box 1 c (hereinafter,refer to as cradle) onto which the portable device 2 can be placed. Theportable device 2 includes a processing part 2 a, a battery 2 b, and aconnection contact 2 c. The processing part la is similar in structureto the main device 1 shown in FIG. 1, and the processing part 2 a issimilar in structure to the portable device 2 shown in FIG. 1.

By placing the portable device 2 on the cradle 1 c, the portable device2 is electrically connected to the main device 1 via the connectioncontact 2 c. Furthermore, in the meantime, the charging part 1 b whichis provided in the main device 1 charges the battery 2 b in the portabledevice 2 through the connection contact 2 c. As the portable device 2 isrelatively-high power, a rechargeable so-called secondary battery ispopular for the battery 2 b provided therein. Consequently, the battery2 b needs to be regularly charged every day, and this thus necessitatesthe portable device 2 to be physically connected to some types ofcharger. According to the second embodiment, when any physicalconnection for the to-be-required charging is made, information such asprograms can be advantageously transferred at the same time. Therefore,rather conveniently, there is no need to make any new connection fortransfer. Note that the charging part 1 b may monitor charging currentand detect the start of a connection, and then notifies the detection tothe processing part 1 a so as to start the transfer processing of theprogram. In this manner, rather conveniently, program transfer isautomatically started by only placing the portable device 2 on thecradle 1 c.

Third Embodiment

FIG. 16 is an outer perspective diagram showing the physical structureof a portable viewing/listening system according to a third embodimentof the present invention. By referring to FIG. 16, in the portableviewing/listening system of the third embodiment, data transfer from themain device 1 to the portable device 2 is done indirectly via arecording medium 3. To be more specific, the recording medium 3 iswritten with information such as a program when being attached to themain device 1, and is read out the internally-stored programinformation, for example, when being attached to the portable device 2.In such a manner, in the third embodiment, program transfer orinformation exchange can be done in a similar manner to the firstembodiment via the recording medium 3. The recording medium 3 includes ahard disk card or a semiconductor recording card in PCMCIA Standards,for example.

In the third embodiment, the main device 1 is provided with a digitalbroadcasting receiver which is equipped with a slot of DVB-CI (DigitalVideo Broadcasting-Common Interface). The DVB-CI is a specification thatis standardized by the standardization group in Europe called DVB, andspecifies the receiver to be equipped with a slot of PCMCIA and the slotto be an insertable type for a descrambler of a PC card in PCMCIAStandards. Accordingly, with a plurality of slots provided and aplurality of descramblers inserted, the receiver can correspond tovarious cryptographic methods. For the DVB-CI, PCMCIA which is normallyequipped with a note-type PC (Personal Computer) as a physical andelectrical interface is used. For some receivers, it is structurallypossible to function in a similar manner to the main device 1 in FIG. 1only by updating a software in the existing digital broadcast receiverby way of a download through broadcasting.

In the third embodiment, the portable device 2 is the note-type PC.Thanks to the improving-performance of the CPU, for example, the videoand audio of the MPEG-2 can be decoded only through software processing.Therefore, only by installing a computer program which executes theprocessing for the portable device in the existing-type of the note-typePC, an operation similar to that of the portable device 2 can beattained. Note that the aforementioned computer program is written tothe recording medium 3 by the main device 1, for example, and then isread out by the portable device 2 and executed. In such a manner, thereis no need to have a special operation in which the program isdownloaded from the network so as to obtain the program in the portabledevice 2.

Fourth Embodiment

FIG. 17 is a block diagram showing the structure of a portableviewing/listening system according to a fourth embodiment of the presentinvention. In the fourth embodiment, it is assumed that an informationsource for the main device 1 is not broadcast but is broadcast-typeservice from a computer network 4 such as Internet.

In the fourth embodiment, the main device 1 is provided with a modem 1d, a PC (personal computer) 1 e, and an MD (Mini Disk) deck 1 f which isused to exchange data in the computer network 4. The modem id, PC 1 e,and MD deck 1 f are interconnected through a high-speed digitalinterface such as IEEE1394. In this example, the PC 1 e functions in asimilar manner to the main device in FIG. 1 by executing a predeterminedcomputer program. The recording medium 3 may include a package mediumsuch as MD.

In the fourth embodiment, the portable device 2 is structured as aaudio-playback-capable digital still camera including an MD drive 2 d, aphotographing part 2 e, an encoding part 2 f, a reproduction (play-back)part 2 g, a display 2 h, a speaker 2 i, and a CPU 2 j. Note that the CPU2 j controls an operation of a predetermined circuit block (for example,the MD drive 2 d, the photographing part 2 e, and the encoding part 2f). By operating the CPU 2 j which is provided for the digital stillcamera in accordance with the predetermined computer program, thedigital still camera is structured to function in a similar manner tothe portable device 2 in FIG. 1 in addition to a typical function for ageneral camera. Note that the recording medium 3 is not limited to theMD. Further, the portable device 2 may directly receive data from themain device 1 in a structure where the main device 1 is connectable tothe portable device 2.

In the embodiments described above, every program data that is stored inthe main device 1 is set to be transferred to the portable device 2.However, only the program data which is selected by the users from amongthe program data that is stored in the main device 1 may be transferredto the portable device 2. If this is the case, the EPG (Electric ProgramGuide) data may be previously transferred from the main device 1 to theportable device 2, and then the users may preselect any program datawhich are desired to be received from the main device 1 while taking alook at the program guide at their convenience. In detail, the maindevice 1 recognizes the programs that are preselected in the portabledevice 2 when the portable device 2 is attached thereto, and thentransfers only the applicable program data to the portable device 2.

INDUSTRIAL APPLICABILITY

The present invention is suitable for a case where a program that isreceived by a main device and stored therein is to be easily enjoyedwith a portable device.

1. A main device which is used in a state of being fixedly orsemi-fixedly installed and which is used to transfer any receivedprogram data to an easy-to-carry portable device, said main devicecomprising: receiving means for receiving program data provided throughbroadcasting; demultiplexing means for demultiplexing the program datareceived by said receiving means into program components, each programcomponent representing data of a multimedia type and spanning a sameplay-back length as the program data; primary storing means for storingthe program components constituting the program data received by saidreceiving means; transfer priority assigning means for assigning atransfer priority and class to each program component constituting theprogram data stored in said primary storing means; transfer prioritydefining means for previously defining default transfer priorities toeach type of the program components; and transferring means fordiscretely transferring, to the portable device, each of the programcomponents of the program data stored in said primary storing means inthe direction of a time axis in order of the transfer priority assignedby said transfer priority means to each program component of the programdata stored in said primary storing means, wherein: said transferpriority assigning means assigns the default transfer priorities to eachof the program components in accordance with a definition provided bysaid transfer priority defining means; said transfer priority definingmeans classifies the class of each program component; program componentsof the program data which are replaceable with each other duringplaying-back are assigned in a same class; and when no program componentin the same class has a value that is defined as being top transferpriority therein, said transfer priority assigning means changes a valueof a program component which is currently assigned the highest transferpriority in the class to the value that is defined as being the toptransfer priority therein.
 2. The main device according to claim 1,wherein said transfer priority assigning means assigns transferpriorities to each of the program components in such a manner that aprogram component with a lesser amount of data has a higher transferpriority.
 3. The main device according to claim 1, wherein, when aplurality of the program data stored in said primary storing means iscollectively transferred to said portable device, said transferringmeans selects any program component having the same transfer priorityfrom each of the program data, combines the selected program componentsinto a unit, and then discretely transfers the combined unit in thedirection of the time axis in order of the transfer priority assigned toeach combined unit.
 4. The main device according to claim 3, whereinsaid transfer priority assigning means checks each class for the defaulttransfer priorities assigned to each of the program components by saidtransfer priority assigning means, and then changes, in accordance witha result of the check, the default transfer priority assigned to each ofthe program components on a class basis, as required.
 5. The main deviceaccording to claim 1, further comprising program component generatingmeans for generating a new program component from the program componentsof the program data received by said receiving means, wherein saidstoring means adds the new program component generated by said programcomponent generating means to the program data received by saidreceiving means, and stores the received program data having the newprogram component added thereto.
 6. A method of transferring programdata received by a fixedly or semi-fixedly installed main device to aneasy-to-carry portable device, said method comprising: receiving programdata provided through broadcasting; demultiplexing the program datareceived in said receiving of the program data into program components,each program component representing data of a multimedia type andspanning a same play-back length as the program data; storing theprogram components constituting the program data received in saidreceiving of the program data; assigning a transfer priority and classto each program component constituting the program data stored in saidstoring of the program data; previously defining default transferpriorities to each type of the program components; discretelytransferring, to the portable device, each of the program components ofthe stored program data in the direction of a time axis in order of thetransfer priority assigned to each program component of the storedprogram data, wherein: said assigning of the transfer priority and classassigns the default transfer priorities to each of the programcomponents in accordance with a definition provided in said previouslydefining of the default transfer priorities; program components of theprogram data which are replaceable with each other during play-back areassigned in a same class; and when no program component in the sameclass has a value that is defined as being top transfer prioritytherein, said assigning of the transfer priority and class changes avalue of the program component which is currently assigned the highestpriority in the class to the value that is defined as being the toptransfer priority therein.